Sorry, Karachi is very polarized, and there’s a lot of hatred and group-baazi amongst the various elasticities, groups, parties, sects etc. The best city in that regards is Islamabad, no question about it. Now you could argue this would happen because of Karachi’s diversity, but then again, Islamabad is diverse too, most of the people aren’t really natives of the city and also, look at NY, the melting pot, a prime example of coexistence.